The mRNA vaccines used to prevent COVID-19 appear to be highly effective against variants of concern, in contrast to the reduced efficacy seen with other vaccine technologies. Read More

The National Advisory Committee on Immunization (NACI) is now recommending that Canadians wait for an mRNA vaccine if they can rather than take the first COVID vaccine they can get (www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html).  Read More

An Oxford University study reports that the incidence of a rare clotting complication, cerebral venous sinus thrombosis (CVST or CVT), is significantly higher with COVID-19 infection compared to after COVID-19 vaccination (Taquet et al. OSF preprint, 14 April 2021; https://osf.io/a9jdq/). The study has not been peer reviewed. Read More

Part 2

The government of Canada has opted to prolong the second COVID-19 vaccination to 16 weeks after the first dose due to a limited vaccine supply. The decision was based on a recommendation from the National Advisory Committee on Immunization (NACI; www.canada.ca/en/public-health/services/immunization/national-advisory-committee-on-immunization-naci/recommendations-use-covid-19-vaccines.html#b1). The rationale is that administering one dose to a wider population will have a greater impact on severe COVID outcomes than giving the required two doses to fewer people. This raises the question: what are the benefits and risks of this partial-immunity approach? Read More